Method of making a tartar control dentifrice containing fluoride and peroxide

ABSTRACT

The present invention relates to a method of manufacturing predominately undissolved pyrophosphate and calcium peroxide compositions comprising the steps of: (a) preparing a mixture of a soluble fluoride ion source and one or more aqueous carrier materials; (b) adding tetrasodium pyrophosphate and calcium peroxide, all at once or in portions, under conditions wherein less than about 20% of the total pyrophosphate and calcium peroxide are dissolved in the mixture, and wherein any further remaining aqueous carrier materials not added to the mixtures during step (a) are added in whole or in part in step (b) or thereafter, either by themselves or with any remaining amount of the tetrasodium pyrophosphate or calcium peroxide under conditions such that less then about 20% of the total pyrophosphate and calcium peroxide are dissolved in the mixture; and (c) heating the mixture.

BACKGROUND OF THE INVENTION

The present invention relates to a method of making stable oralcompositions containing fluoride, pyrophosphate, and calcium peroxide.

Oral compositions utilizing a peroxide component are known. The mostwidely used peroxide has been hydrogen peroxide. Compositions containingperoxide generally deliver benefits in the antiplaque and antigingivitisareas. Other cosmetic benefits, such as tooth whitening, may also beprovided. Oral compositions formulated with peroxide, a highly reactiveingredient, generally exhibit poor stability and many products do nothave consumer preferred aesthetics.

While peroxide executions have been developed, they present a processingchallenge. Producing peroxide compositions also containing tartarcontrol ingredients and fluoride in the same phase is even moredifficult. It is difficult to stabilize the peroxide in the presence offluoride and tartar control ingredients, without producing a productwhich has negative aesthetics and tartar control efficacy concerns.

References disclosing peroxide containing compositions include U.S. Pat.5,403,578, to Gordon, issued Apr. 4, 1995, which discloses an oralcomposition containing peroxide, a tartar control ingredient, andfluoride. To stabilize the peroxide, the peroxide is microencapsulatedto avoid the peroxide reacting with the other ingredients. U.S. Pat.Nos. 5,456,902, to Williams, et al., issued Oct. 10, 1995, and5,372,803, to Williams, et al., issued Dec. 13, 1994, disclose acomposition utilizing a dual-compartment dispenser which separates theperoxide phase from the tartar control ingredients. WO 95/09603,published Apr. 13, 1995, also discloses a dual-compartment containerwhich separates a calcium peroxide phase from the other dentifricephase.

Canadian published applications 2,162,821, 2,162,885, and 2,162,812, allpublished May 15, 1996, disclose the use of calcium peroxide in adentifrice. The amount of the water is controlled in these applicationsto aid in the stability.

Although peroxide products containing tartar control ingredients andfluoride are known, there is a continuing need to develop improvedproducts. The present inventors have discovered a method for makingstable oral compositions comprising fluoride, pyrophosphate, and calciumperoxide. It has also been discovered that these oral compositions maybe formulated to contain an alkali metal bicarbonate salt and xylitolwhile still maintaining good stability.

It is therefore an object of the present invention to provide a methodfor making a stable tartar control composition that contains fluorideand calcium peroxide. It is also an object of the present invention toprovide a method for making a tartar control composition that containsfluoride, calcium peroxide, an alkali metal bicarbonate salt, andxylitol. A further object of the present invention is to provide amethod of making which is easily controlled and which produces productshaving improved aesthetics.

These and other objects of the present invention will become readilyapparent from the detailed description which follows.

All percentages and ratios used herein are by weight of the totalcomposition, and all measurements are made at 25° C., unless otherwisespecified.

SUMMARY OF THE INVENTION

The present invention relates to a method of manufacturing predominatelyundissolved pyrophosphate and calcium peroxide compositions comprisingthe steps of: (a) preparing a mixture of a soluble fluoride ion sourceand one or more aqueous carrier materials; (b) adding tetrasodiumpyrophosphate and calcium peroxide, all at once or in portions, underconditions wherein less than about 20% of the total pyrophosphate andcalcium peroxide are dissolved in the mixture, and wherein any furtherremaining aqueous carrier materials not added to the mixtures duringstep (a) are added in whole or in part in step (b) or thereafter, eitherby themselves or with any remaining amount of the tetrasodiumpyrophosphate or calcium peroxide under conditions such that less thenabout 20% of the total pyrophosphate and calcium peroxide are dissolvedin the mixture; and (c) heating the mixture to a temperature range offrom about 38° C. to about 71° C. The dentifrice will have a viscosityof from about 10 to about 60 Brookfield units at 23° C. in bulk orpacked product from about 10 minutes to about two hours after being madeor packed and the viscosity builds to about 30 to about 125 Brookfieldunits at 23° C. in bulk or packed product after about one month or moreafter being made or packed.

The present invention also relates to a method for making an oralcomposition comprising a soluble fluoride source capable of providingfrom about 50 ppm to about 3500 ppm of free fluoride ions, an amount ofat least about 1.5% tetrasodium pyrophosphate, from about 0.01% to about5% of calcium peroxide; and from about 80% to about 98% of one or moreaqueous carriers, wherein the oral composition has a neat pH of fromabout 9.0 to about 10.5 and a total water content of from about 5% toabout 20%. The composition may also include from about 0.5% to about 40%of an alkali metal bicarbonate salt and from about 0.01% to about 25% ofxylitol.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a method for making an oralcompositions comprising fluoride, tetrasodium pyrophosphate, and calciumperoxide. These compositions can also include an alkali metalbicarbonate salt and xylitol.

The oral compositions of the present invention may be in the form of ato toothpaste. The term "toothpaste", as used herein, means paste, gel,or liquid formulations unless otherwise specified. The toothpaste may bein any desired form, such as deep striped, surface striped,multilayered, having the gel surrounding the paste, or any combinationthereof. The toothpaste may also be a multilayer composition which isextruded from the tube in combination paste/gel stripes. One of thelayers must comprise all of the essential components, while the otherlayers may contain less than all of the essential components or may beany dentifrice formulation.

The term "oral composition" as used herein means a product which in theordinary course of usage is not intentionally swallowed for purposes ofsystemic administration of particular therapeutic agents, but is ratherretained in the oral cavity for a time sufficient to contactsubstantially all of the dental surfaces and/or oral tissues forpurposes of oral activity.

The term "aqueous carrier" as used herein means any safe and effectivematerials for use in the compositions of the present invention. Suchmaterials include thickening materials, humectants, water, bufferingagents, abrasive polishing materials, surfactants, titanium dioxide,flavor systems, sweetening agents, coloring agents, and mixturesthereof.

The present compositions comprise essential components, as well asoptional components. The essential and optional components of thecompositions of the present invention are described in the followingparagraphs.

Fluoride Ion Source

The present invention incorporates a soluble fluoride source capable ofproviding free fluoride ions. Preferred soluble fluoride ion sourcesinclude sodium fluoride, stannous fluoride, indium fluoride, and sodiummonofluorophosphate. Sodium fluoride is the most preferred solublefluoride ion source. Norris et al., U.S. Pat. No. 2,946,725, issued Jul.26, 1960, and Widder et al., U.S. Pat. No. 3,678,154 issued Jul. 18,1972, disclose such fluoride ion sources as well as others. Both patentsare incorporated herein by reference in their entirety.

The present compositions contain a soluble fluoride source capable ofproviding from about 50 ppm to about 3500 ppm, and preferably from about500 ppm to about 3000 ppm of free fluoride ions.

Pyrophosphate Source

The present invention includes a pyrophosphate source. The pyrophosphatesource comprises predominately undissolved pyrophosphate. Undissolvedpyrophosphate compositions are defined as compositions containing nomore than about 20% of the total pyrophosphate salt dissolved in thecomposition, preferably less than about 10% of the total pyrophosphatedissolved in the composition. Tetrasodium pyrophosphate salt is thepreferred pyrophosphate salt in these compositions. It is also preferredthat tetrasodium pyrophosphate be the only pyrophosphate or tartarcontrol agent used.

Tetrasodium pyrophosphate may be the anhydrous salt form or thedecahydrate form, or any other species stable in solid form in thedentifrice compositions. The anhydrous salt is in its solid particleform, which may be its crystalline and/or amorphous state, with theparticle size of the salt preferably being small enough to beaesthetically acceptable and readily soluble during use. The amount ofpyrophosphate salt useful in making these compositions is any tartarcontrol effective amount, and is generally from about 1.5% to about 15%,preferably from about 2% to about 10%, and most preferably from about 3%to about 8%, by weight of the dentifrice composition. Some or all of thetetrasodium pyrophosphate is undissolved in the product and is presentas tetrasodium pyrophosphate particles. Pyrophosphate ions in differentprotonated states (e.g., HP₂ O₇ ⁻³) may also exist depending upon the pHof the composition and if part of the tetrasodium is dissolved.

The pyrophosphate salts are described in more detail in Kirk & Othmer,Encyclopedia of Chemical Technology, Third Edition, Volume 17,Wiley-Interscience Publishers (1982), incorporated herein by referencein its entirety, including all references incorporated into Kirk &Othmer.

Optional anticalculus agents that may be used in combination with thepyrophosphate salt include such known materials as synthetic anionicpolymers including polyacrylates and copolymers of maleic anhydride oracid and methyl vinyl ether (e.g., Gantrez), as described, for example,in U.S. Pat. No. 4,627,977, to Gaffar et al., the disclosure of which isincorporated herein by reference in its entirety; as well as, e.g.,polyamino propoane sulfonic acid (AMPS)!, zinc citrate trihydrate,polyphosphates (e.g., tripolyphosphate; hexametaphosphate),diphosphonates (e.g., EHDP; AHP), polypeptides (such as polyaspartic andpolyglutamic acids), and mixtures thereof.

Calcium Peroxide

The present invention also includes calcium peroxide. The followingamounts represent the amount of peroxide raw material, although thecalcium peroxide may contain ingredients other than the peroxide rawmaterial. The present compositions contain from about 0.01% to about 5%,preferably from about 0.1% to about 3%, more preferably from about 0.2%to about 1%, and most preferably from about 0.3% to about 0.8% ofcalcium peroxide, by weight of the total composition.

pH

The pH of the present compositions is adjusted to a neat pH range offrom about 9.0 to about 10.5. The term "neat pH", as used herein, isdefined as the pH of the composition before the composition is dilutedor contacted by the mouth. The neat pH is adjusted by the use ofbuffering agents. The neat pH of the present composition is from about9.0 to about 10.5, preferably from about 9.2 to about 10.2, and morepreferably from about 9.5 to about 10.

Water

Water is also contained in the present invention. Water used in thepreparation of these compositions should preferably be of low ioncontent and free of organic impurities. The "total water content" of thecomposition, as used herein, includes the free water which is added plusthe water which is introduced with other materials, such as withsorbitol, silica, color solutions, or surfactant solutions. The totalwater content of the present invention is from about 5% to about 20%,preferably from about 9% to about 14%, more preferably from about 9.1%to about 13%, and most preferably from about 10% to about 11%, by weightof the total composition.

Alkali Metal Bicarbonate salt

The present invention may also include an alkali metal bicarbonate salt.Alkali metal bicarbonate salts are soluble in water and unlessstabilized, tend to release carbon dioxide in an aqueous system. Sodiumbicarbonate, also known as baking soda, is the preferred alkali metalbicarbonate salt. The present compositions may contain from about 0.5%to about 40%, preferably from about 0.5% to about 20%, more preferablyfrom about 0.5% to about 5%, and most preferably from about 0.8% toabout 2% of an alkali metal bicarbonate salt, by weight of the totalcomposition.

Xylitol

The present invention may also include xylitol. Xylitol is a sugaralcohol that is used as a sweetener and humectant. Xylitol may provide atherapeutic effect, such as an antibacterial or anticaries effect. Thepresent compositions may comprise xylitol at a level from about 0.01% toabout 25%, preferably from about 3% to about 15%, more preferably fromabout 5% to about 12%, and most preferably from about 9% to about 11%,by weight of the total composition.

Aqueous Carriers

In preparing the present compositions, it is desirable to add one ormore aqueous carriers to the compositions. Aqueous carriers containmaterials that are well known in the art and readily chosen by oneskilled in the art based on the physical and aesthetic propertiesdesired for the compositions being prepared. Aqueous carriers typicallycomprise from about 80% to about 98%, and preferably from about 85% toabout 95%, by weight of the total composition.

The present invention compositions in the form of toothpastes, typicallycontain some thickening material or binders to provide a desirableconsistency.

Preferred thickening agents are carboxyvinyl polymers, carrageenan,hydroxyethyl cellulose, and water soluble salts of cellulose ethers suchas sodium carboxymethylcellulose and sodium carboxymethyl hydroxyethylcellulose. Natural gums such as gum karaya, xanthan gum, gum arabic, andgum tragacanth can also be used. Colloidal magnesium aluminum silicate,lithium aluminum magnesium silicate (trade name Laponite), or finelydivided silica can be used as part of the thickening agent to furtherimprove texture. Thickening agents can be used in an amount of fromabout 0. 1% to about 15%, by weight of the total composition.

Another optional component of the compositions desired herein is ahumectant. The humectant serves to keep toothpaste compositions fromhardening upon exposure to air and certain humectants can also impartdesirable sweetness of flavor to toothpaste compositions. Suitablehumectants for use in the invention include glycerin, sorbitol,polyethylene glycol, propylene glycol, and other edible polyhydricalcohols. Polyethylene glycols are one of the preferred humectants.

Polyethylene glycols useful herein are those which are liquids at roomtemperature or have a melting point slightly there above. Liquid andlow-melting polyethylene glycols are commercially available from UnionCarbide under the Carbowax® tradename. Preferred are those polyethyleneglycols having a molecular weight range of from about 200 to about 2000and corresponding n values of from about 4 to about 40. More preferredare polyethylene glycols having a molecular weight range of from about400 to about 1600 and most preferred are polyethylene glycols having amolecular weight range of from about 570 to about 630. The humectantgenerally comprises from about 0% to 70%, and preferably from about 15%to 55%, by weight of the compositions herein.

Buffering agents may be used to adjust the pH of the presentcompositions. Buffering agents, as used herein, refer to agents that canbe used to adjust the pH of the compositions to a neat pH range of fromabout 9.0 to about 10.5. These agents include alkali metal hydroxides,carbonates, sesquicarbonates, borates, and silicates. Specific agentsinclude monosodium phosphate, trisodium phosphate, sodium hydroxide,sodium carbonate, and potassium hydroxide. Buffering agents can be usedat a level of from about 0.5% to about 10%, by weight of the presentcompositions.

An abrasive polishing material may also be included in the toothpastecompositions. The abrasive polishing material contemplated for use inthe compositions of the present invention can be any material which doesnot excessively abrade dentin. These include, for example, silicasincluding gels and precipitates, calcium carbonate, dicalciumorthophosphate dihydrate, calcium pyrophosphate, tricalcium phosphate,calcium polymetaphosphate, insoluble sodium polymetaphosphate, hydratedalumina, and resinous abrasive materials such as particulatecondensation products of urea and formaldehyde, and others such asdisclosed by Cooley et al in U.S. Pat. No. 3,070,510, issued Dec. 25,1962, incorporated herein by reference. Mixtures of abrasives may alsobe used.

Silica dental abrasives of various types are preferred because of theirunique benefits of exceptional dental cleaning and polishing performancewithout unduly abrading tooth enamel or dentine. The silica abrasivepolishing materials herein, as well as other abrasives, generally havean average particle size ranging between about 0.1 to about 30 microns,and preferably from about 5 to about 15 microns. The abrasive can beprecipitated silica or silica gels such as the silica xerogels describedin Pader et al., U.S. Pat. No. 3,538,230, issued Mar. 2, 1970, andDiGiulio, U.S. Pat. No. 3,862,307, issued Jan. 21, 1975, bothincorporated herein by reference. Preferred are the silica xerogelsmarketed under the trade name "Syloid" by the W. R. Grace & Company,Davison Chemical Division. Also preferred are the precipitated silicamaterials such as those marketed by the J. M. Huber Corporation underthe trade name, "Zeodent", particularly the silica carrying thedesignation "Zeodent II 9". The types of silica dental abrasives usefulin the toothpastes of the present invention are described in more detailin Wason, U.S. Pat. No. 4,340,583, issued Jul. 29, 1982, incorporatedherein by reference. The abrasive in the toothpaste compositionsdescribed herein is generally present at a level of from about 6% toabout 70% by weight of the composition. Preferably, toothpastes containfrom about 10% to about 50% of abrasive, by weight of the composition.

The present composition may also comprise surfactants, also commonlyreferred to as sudsing agents. Suitable surfactants are those which arereasonably stable and foam throughout a wide pH range. The surfactantmay be anionic, nonionic, amphoteric, zwitterionic, cationic, ormixtures thereof. Anionic surfactants useful herein include thewater-soluble salts of alkyl sulfates having from 8 to 20 carbon atomsin the alkyl radical (e.g., sodium alkyl sulfate) and the water-solublesalts of sulfonated monoglycerides of fatty acids having from 8 to 20carbon atoms. Sodium lauryl sulfate and sodium coconut monoglyceridesulfonates are examples of anionic surfactants of this type. Othersuitable anionic surfactants are sarcosinates, such as sodium lauroylsarcosinate, taurates, sodium lauryl sulfoacetate, sodium lauroylisethionate, sodium laureth carboxylate, and sodium dodecylbenzenesulfonate. Mixtures of anionic surfactants can also be employed.Many suitable anionic surfactants are disclosed by Agricola et al., U.S.Pat. 3,959,458, issued May 25, 1976, incorporated herein in its entiretyby reference. Nonionic surfactants which can be used in the compositionsof the present invention can be broadly defined as compounds produced bythe condensation of alkylene oxide groups (hydrophilic in nature) withan organic hydrophobic compound which may be aliphatic or alkyl-aromaticin nature. Examples of suitable nonionic surfactants include poloxamers(sold under trade name Pluronic), polyoxyethylene sorbitan esters (soldunder trade name Tweens), fatty alcohol ethoxylates, polyethylene oxidecondensates of alkyl phenols, products derived from the condensation ofethylene oxide with the reaction product of propylene oxide and ethylenediamine, ethylene oxide condensates of aliphatic alcohols, long chaintertiary amine oxides, long chain tertiary phosphine oxides, long chaindialkyl sulfoxides, and mixtures of such materials. The amphotericsurfactants useful in the present invention can be broadly described asderivatives of aliphatic secondary and tertiary amines in which thealiphatic radical can be a straight chain or branched and wherein one ofthe aliphatic substituents contains from about 8 to about 18 carbonatoms and one contains an anionic water-solubilizing group, e.g.,carboxylate, sulfonate, sulfate, phosphate, or phosphonate. Othersuitable amphoteric surfactants are betaines, specificallycocamidopropyl betaine. Mixtures of amphoteric surfactants can also beemployed. Many of these suitable nonionic and amphoteric surfactants aredisclosed by Gieske et al., U.S. Pat. No. 4,051,234, issued Sep. 27,1977, incorporated herein by reference in its entirety. The presentcompositions may comprise one or more surfactants each at a level offrom about 0.25% to about 10%, preferably from about 0.5% to about 8%,and most preferably from about 1% to about 6%, by weight of thecomposition.

Titanium dioxide may also be added to the present composition. Titaniumdioxide is a white powder which adds opacity to the compositions.Tidioxide dioxide generally comprises from about 0.25% to about5compositions.

Coloring agents may also be added to the present composition. Thecoloring agent may be in the form of an aqueous solution, preferably a1% color solution. Color solutions may comprise from about 0.01% toabout 5%, by weight of the composition.

A flavor system can also be added to the compositions. Suitableflavoring components include oil of wintergreen, oil of peppermint, oilof spearmint, clove bud oil, menthol, anethole, methyl salicylate,eucalyptol, cassia, 1-menthyl acetate, sage, eugenol, parsley oil,oxanone, alpha-irisone, marjoram, lemon, orange, propenyl guaethol,cinnamon, vanillin, ethyl vanillin, heliotropine, 4-cis-heptenal,diacetyl, methyl-para-tert-butyl phenyl acetate, and mixtures thereof.Coolants may also be part of the flavor system. Preferred coolants inthe present compositions are the paramenthan carboxyamide agents such asN-ethyl-p-menthan-3-carboxamide (known commercially as "WS-3") andmixtures thereof. A flavor system is generally used in the compositionsat levels of from about 0.001% to about 5%, by weight of thecomposition.

Sweetening agents can be added to the compositions. These include sodiumsaccharin, dextrose, sucrose, lactose, maltose, levulose, aspartame,sodium cyclamate, D-tryptophan, dihydrochalcones, acesulfame, andmixtures thereof. Sweetening agents are generally used in toothpastes atlevels of from about 0.005% to about 5%, by weight of the composition.

The present invention may also include other agents. Included among suchagents are water insoluble non-cationic agents such as triclosan andother agents of the type disclosed in Parran, Jr. et al., U.S. Pat. No.5,015,466, issued May 14, 1991, incorporated by reference herein in itsentirety.

The composition may be a multilayer toothpaste composition. Thiscomposition may comprise two or more separate layers which are incontact with each other. Preferably, the separate layers are pastes andgels that when extruded from the tube, appear as combination paste/gelstripes. One of the layers in this paste/gel stripe combination mustcomprise all of the essential components, while the other layers maycontain less than all of the essential components or may be anydentifrice formulation. Preferably, the gel layers do not comprise theessential component of calcium peroxide.

Alternatively, the dentifrice compositions may be physically separatedin a dentifrice dispenser. The dispenser may be a tube, pump, or anyother container suitable for dispensing toothpaste. Dual compartmentpackages suitable for this purpose are described in U.S. Pat. No.4,528,180, issued Jul. 9, 1985; U.S. Pat. 4,687,663, issued Aug. 18,1987; and 4,849,213, issued Jul. 18, 1989, all to Shaeffer, allincorporated herein in their entirety. The dispenser will deliverapproximately equal amounts of each dentifrice composition through anopening. The compositions may intermix once dispensed. Alternatively,the oral formulation may be delivered from a kit containing two separatedispensers which are used to deliver two dentifrice compositions thatare both used simultaneously.

Method of Manufacturing

This method enables the composition to maintain a stable matrix offluoride, a predominately undissolved pyrophosphate salt, and calciumperoxide. The method of manufacturing comprises the steps of: (a)preparing a mixture of a soluble fluoride ion source and one or moreaqueous carrier materials; (b) adding tetrasodium pyrophosphate andcalcium peroxide, all at once or in portions, under conditions whereinless than about 20% of the total pyrophosphate and calcium peroxide aredissolved in the mixture; and wherein further any remaining aqueouscarrier materials not added to the mixture during step (a) are added inwhole or in part in step (b) or thereafter, either by themselves or withany remaining amount of the tetrasodium pyrophosphate or calciumperoxide, under conditions such that less than about 20% of the totalpyrophosphate and calcium peroxide are dissolved in the mixture; and (c)heating the mixture to a temperature range of from about 38° C. (100°F.) to about 71° C. (160° F.) and preferably to a temperature range offrom about 52° C. (125° F.) to about 57° C. (135° F.). The amount ofpyrophosphate dissolved in the mixture for the methods and compositionsof the present invention is preferably less than about 10% by weight ofthe total pyrophosphate present in the compositions and the amount ofcalcium peroxide dissolved in the mixtures is preferably less than about10% by weight of the total amount of calcium peroxide present in thecompositions.

The dentifrice mixtures will have a viscosity of from about 10 to about60 Brookfield units at 23° C. in bulk or packed product from about 10minutes to about two hours after being made or packed. The viscositythen builds to a viscosity of from about 30 to about 125 Brookfieldunits at 23° C. in bulk or packed product after about one month or moreafter being made or packed. Preferably, the viscosity is from about 20to about 50 Brookfield units at 23° C. in bulk or packed product fromabout 10 minutes to about two hours after being made or packed and theviscosity builds to a viscosity of from about 60 to about 80 Brookfieldunits at 23° C. in bulk or packed product after about one month or moreafter being made or packed. The viscosity is measured with a BrookfieldSynchrolectric Viscometer Model RVT/2 using a T-E spindle at 2.5revolutions per minute.

Preferably, one or more of the following process conditions arecontrolled as follows to limit the solubility of the tetrasodiumpyrophosphate and calcium peroxide in the dentifrice mixture: (1) theneat pH of the mixture is above about pH 8, preferably above about pH 9,during and after the tetrasodium pyrophosphate and calcium peroxideadditions are made to the mixture; and (2) the tetrasodium pyrophosphatesalt and peroxide are two of the last components to be added to themixture, preferably after all or much of the other sodium-containingsalts present in the composition have been added to the process mixture.By these methods, the dissolved tetrasodium pyrophosphate salt is lesslikely to recrystalize in the form of glass-like crystal particles oftetrasodium pyrophosphate decahydrate and the peroxide is less likely tobreakdown and react with the fluoride to form calcium fluoride.

During step (c), the heating step, the mixture is heated to atemperature range of about 38° C. (100° F.) to about 71° C. (1600 F) andpreferably to a temperature range of from about 52° C. (125° F.) toabout 57° C. (135° F.). One or more heating variables may be controlledduring this step. The heating variables include: the rate of heating themixture to the temperature range, the amount of time that thecomposition is kept at this temperature range, and the rate of coolingthe mixture from the temperature range. Additionally, another heatingvariable is homogenization. Homogenization of the mixture may occurwhile the mixture is within the temperature range.

After step (c), the toothpaste is fed into a suitable dispensing tube orcontainer. After filling the tube with toothpaste, the open end of thetube is sealed. If the toothpaste is to be a multilayer composition, thedesired toothpaste layers are fed in parallel streams to form amultilayered appearance and then the open end of the tube is sealed. Thedentifrice layers will be extruded in the desired multilayerconfiguration when dispensed from the tube.

Method of Treatment

The present invention compositions additionally relate to a method forreducing the incidence of calculus on dental enamel. The method oftreatment herein comprises contacting the dental enamel surfaces in themouth with the oral compositions according to the present invention.

The following examples further describe and demonstrate embodimentswithin the scope of the present invention. These examples are givensolely for the purpose of illustration and are not to be construed aslimitations of the present invention as many variations thereof arepossible without departing from the spirit and scope.

    ______________________________________                                        EXAMPLE I                                                                     Ingredient         Weight %                                                   ______________________________________                                        Glycerin           29.761                                                     Polyethylene Glycol 12                                                                           1.000                                                      Xanthan Gum        0.500                                                      Carboxymethylcellulose                                                                           0.350                                                      Water              6.500                                                      Sodium Saccharin   0.450                                                      Sodium Fluoride    0.243                                                      Sodium Alkyl Sulfate.sup.(a)                                                                     6.000                                                      Flavor             1.150                                                      Sodium Carbonate   2.500                                                      Titanium Dioxide   1.000                                                      Silica             20.000                                                     Sodium Bicarbonate 15.000                                                     Propylene Glycol   10.000                                                     Tetrasodium Pyrophosphate                                                                        5.046                                                      Calcium Peroxide   0.500                                                      ______________________________________                                    

Example I is prepared as follows: Add approximately half of the glycerinto a mixing vessel. Disperse the thickening agents, carboxymethylcellulose and xanthan gum, in the propylene glycol. Add this mixture ofdispersed thickening agents in propylene glycol to the mixing vessel andadd the polyethylene glycol. Dissolve the sodium fluoride and sodiumsaccharin in water and add to the mixture. The flavor and sodium alkylsulfate are then added. Next, add the sodium carbonate, titaniumdioxide, and the silica. Add the sodium bicarbonate. Disperse thetetrasodium pyrophosphate in the remaining glycerin and add to themixture. Finally, add the calcium peroxide. Stir the mixture untilhomogeneous and then heat the mixture to a temperature range of fromabout 110° F. to about 160° F. This temperature should be maintained forabout 30-60 minutes. Finally, the mixture may be cooled and deaerated.

    ______________________________________                                        EXAMPLE II                                                                    Ingredient         Weight %                                                   ______________________________________                                        Glycerin           32.700                                                     Xanthan Gum        0.200                                                      Carboxymethylcellulose                                                                           0.150                                                      Water              3.700                                                      Sodium Saccharin   0.500                                                      Sodium Fluoride    0.243                                                      Xylitol            10.000                                                     Poloxamer 407      2.000                                                      Sodium Alkyl Sulfate.sup.(a)                                                                     6.000                                                      Flavor             1.000                                                      Sodium Carbonate   2.000                                                      Color.sup.(b)      1.000                                                      Silica             20.700                                                     Sodium Bicarbonate 1.000                                                      Propylene Glycol   11.765                                                     Tetrasodium Pyrophosphate                                                                        6.575                                                      Calcium Peroxide   0.467                                                      ______________________________________                                    

Example II is prepared as follows: Add approximately half of theglycerin to a mixing vessel. Disperse the thickening agents,carboxymethyl cellulose and xanthan gum, in the humectant, propyleneglycol. Add this mixture of dispersed thickening agents in humectant tothe mixing vessel. Dissolve the sodium fluoride and sodium saccharin inwater and add to the mixture. Add the xylitol and poloxamer. The flavorand sodium alkyl sulfate should then be added. Next, add the sodiumcarbonate and silica. Add the sodium bicarbonate. Coloring agents may beadded at any time. Disperse the tetrasodium pyrophosphate in theremaining glycerin and add to the mixture. Finally, add the calciumperoxide. Stir the mixture until homogeneous and then heat the mixtureto a temperature range of from about 110° F. to about 160° F. Thistemperature should be maintained for about 30-60 minutes. Finally, themixture may be cooled and deaerated.

    ______________________________________                                        EXAMPLE III                                                                   Ingredient         Weight %                                                   ______________________________________                                        Glycerin           26.589                                                     Polyethylene Glycol 6                                                                            5.000                                                      Xanthan Gum        0.200                                                      Carboxymethylcellulose                                                                           0.150                                                      Water              3.750                                                      Sodium Saccharin   0.500                                                      Sodium Fluoride    0.243                                                      Xylitol            10.000                                                     Poloxamer 407      1.000                                                      Sodium Alkyl Sulfate.sup.(a)                                                                     6.000                                                      Flavor             1.000                                                      Sodium Carbonate   2.000                                                      Color.sup.(b)      0.002                                                      Silica             20.700                                                     Sodium Bicarbonate 5.000                                                      Propylene Glycol   12.200                                                     Tetrasodium Pyrophosphate                                                                        5.046                                                      Calcium Peroxide   0.620                                                      ______________________________________                                    

Example III is prepared as follows: Add approximately half of theglycerin to a mixing vessel. Disperse the thickening agents,carboxymethyl cellulose and xanthan gum, in the propylene glycol. Addthis mixture of dispersed thickening agents in propylene glycol to themixing vessel and add the polyethylene glycol. Dissolve the sodiumfluoride and sodium saccharin in water and add to the mixture. Add thexylitol and poloxamer. The flavor and sodium alkyl sulfate are thenadded. Next, add the sodium carbonate and silica. Add the sodiumbicarbonate. Coloring agents may be added at any time. Disperse thetetrasodium pyrophosphate in the remaining glycerin and add to themixture. Finally, add the calcium peroxide. Stir the mixture untilhomogeneous and then heat the mixture to a temperature range of fromabout 110° F. to about 160° F. This temperature should be maintained forabout 30-60 minutes. Finally, the mixture may be cooled and deaerated.

    ______________________________________                                        EXAMPLE IV                                                                    Ingredient         Weight %                                                   ______________________________________                                        Glycerin           32.207                                                     Xanthan Gum        0.200                                                      Carboxymethylcellulose                                                                           0.150                                                      Water              3.750                                                      Sodium Saccharin   0.500                                                      Sodium Fluoride    0.243                                                      Xylitol            10.000                                                     Poloxamer 407      2.000                                                      Sodium Alkyl Sulfate.sup.(a)                                                                     6.000                                                      Flavor             1.000                                                      Sodium Carbonate   2.000                                                      Color.sup.(b)      0.002                                                      Silica             20.700                                                     Sodium Bicarbonate 1.000                                                      Propylene Glycol   14.735                                                     Tetrasodium Pyrophosphate                                                                        5.046                                                      Calcium Peroxide   0.467                                                      ______________________________________                                    

Example IV is prepared as follows: Add approximately half of theglycerin to a mixing vessel. Disperse the thickening agents,carboxymethyl cellulose and xanthan gum, in the humectant, propyleneglycol. Add this mixture of dispersed thickening agents in humectant tothe mixing vessel. Dissolve the sodium fluoride and sodium saccharin inwater and add to the mixture. Add the xylitol and poloxamer. The flavorand sodium alkyl sulfate are then added. Next, add the sodium carbonateand silica. Add the sodium bicarbonate. Coloring agents may be added atany time. Disperse the tetrasodium pyrophosphate in the remainingglycerin and add to the mixture. Finally, add the calcium peroxide. Stirthe mixture until homogeneous and then heat the mixture to a temperaturerange of from about 110° F. to about 160° F. This temperature should bemaintained for about 30-60 minutes. Finally, the mixture may be cooledand deaerated.

    ______________________________________                                        EXAMPLE V                                                                     Ingredient         Weight %                                                   ______________________________________                                        Glycerin           27.050                                                     Polyethylene Glycol 12                                                                           2.000                                                      Xanthan Gum        0.300                                                      Carboxymethylcellulose                                                                           0.200                                                      Water              5.000                                                      Sodium Saccharin   0.450                                                      Sodium Fluoride    0.243                                                      Xylitol            10.000                                                     Poloxamer 407      2.000                                                      Sodium Alkyl Sulfate.sup.(a)                                                                     6.000                                                      Flavor             1.100                                                      Sodium Carbonate   2.600                                                      Titanium Dioxide   1.000                                                      Silica             20.000                                                     Sodium Bicarbonate 1.500                                                      Propylene Glycol   13.947                                                     Tetrasodium Pyrophosphate                                                                        6.116                                                      Calcium Peroxide   0.500                                                      ______________________________________                                         .sup.(a) 27.9% solution of sodium alkyl sulfate in water                      .sup.(b) 1% solution of FD&C Blue #1 in water and preservative           

Example V is prepared as follows: Add approximately half of the glycerinto a mixing vessel. Disperse the thickening agents, carboxymethylcellulose and xanthan gum, in the propylene glycol. Add this mixture ofdispersed thickening agents in propylene glycol to the mixing vessel andadd the polyethylene glycol. Dissolve the sodium fluoride and sodiumsaccharin in water and add to the mixture. Add the xylitol andpoloxamer. The flavor and sodium alkyl sulfate are then added. Next, addthe sodium carbonate, titanium dioxide, and the silica. Add the sodiumbicarbonate. Disperse the tetrasodium pyrophosphate in the remainingglycerin and add to the mixture. Finally, add the calcium peroxide. Stirthe mixture until homogeneous and then heat the mixture to a temperaturerange of from about 110° F. to about 160° F. This temperature should bemaintained for about 30-60 minutes. Finally, the mixture may be cooledand deaerated.

What is claimed is:
 1. A method of manufacturing predominatelyundissolved pyrophosphate and calcium peroxide dentifrice compositionscomprising the steps of:a. preparing a mixture of a soluble fluoride ionsource and one or more aqueous carrier materials; b. adding tetrasodiumpyrophosphate and calcium peroxide, all at once or in portions, underconditions wherein less than about 20% of the total pyrophosphate andcalcium peroxide are dissolved in the mixture, and wherein any furtherremaining aqueous carrier materials not added to the mixture during step(a) are added in whole or in part in step (b) or thereafter, either bythemselves or with any remaining amount of the tetrasodium pyrophosphateor calcium peroxide under conditions such that less than about 20% ofthe total pyrophosphate and calcium peroxide are dissolved in themixture; and c. heating the mixture to a temperature range of from about38° C. to about 71° C.;and wherein the dentifrice has a viscosity offrom about 10 to about 60 Brookfield units at 23° C. in bulk or packedproduct from about 10 minutes to about two hours after being made orpacked and the viscosity builds to about 30 to about 125 Brookfieldunits at 23° C. in bulk or packed product after about one month or moreafter being made or packed.
 2. The method of manufacturing a compositionaccording to claim 1 wherein the tetrasodium pyrophosphate and calciumperoxide are added to the mixture after all other sodium-containingsalts present in the composition have been added to the mixture.
 3. Themethod of manufacturing a composition according to claim 2 wherein themixture has a neat pH of above about pH 8 during and after thetetrasodium pyrophosphate and calcium peroxide additions are made to themixture.
 4. The method of manufacturing a composition according to claim1 (c) further comprising controlling one or more heating variablesselected from the group consisting of rate of heating the mixture to atemperature range of from about 38° C. to about 71° C., amount of timemixture is kept at the temperature range, rate of cooling the mixturefrom the temperature range, homogenization of the mixture while themixture is within the temperature range, and combinations thereof. 5.The method of manufacturing a composition according to claim 4 whereinthe tetrasodium pyrophosphate is in an amount of at least about 1.5%. 6.The method of manufacturing a composition according to claim 5 whereinthe calcium peroxide is in an amount of from about 0.01% to about 5%. 7.The method of manufacturing a composition according to claim 6 whereinthe soluble fluoride ion source is sodium fluoride and is capable ofproviding from about 50 ppm to about 3500 ppm of free fluoride ions. 8.The method of manufacturing a composition according to claim 7 whereinthe composition has a neat pH of from about 9.0 to about 10.5.
 9. Themethod of manufacturing a composition according to claim 8 wherein thecomposition has a total water content of from about 5% to about 20%. 10.The method of manufacturing a composition according to claim 9 whereinfrom about 0.5% to about 40% of an alkali metal bicarbonate salt isadded in step 1 (a).
 11. The method of manufacturing a compositionaccording to claim 10 wherein from about from about 0.01% to about 25%of xylitol is added in step 1 (a).
 12. The method of manufacturing acomposition according to claim 11 wherein from about 0.25% to about 10%of a nonionic surfactant is added in step 1 (a).
 13. The method ofmanufacturing a composition according to claim 12 wherein the nonionicsurfactant is poloxamer.
 14. The method of manufacturing a compositionaccording to claim 13 wherein from about 80% to about 98% of one or moreof the aqueous carriers materials are added in step 1 (a).
 15. Themethod of manufacturing a composition according to claim 14 wherein theaqueous carriers contain materials selected from the group consisting ofthickening materials, humectants, water, buffering agents, surfactants,abrasive polishing materials, sweetening agents, flavor systems,coloring agents, titanium dioxide, and mixtures thereof.